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    <meta charset="UTF-8" />
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    <title>Document</title>
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  <body>
    <script>
      //   声明和赋值结合
      var a = 1;
      console.log(a);
      console.log(typeof a);
      //   声明和赋值分开
      var b;
      b = "你好，世界";
      console.log(b);
      console.log(typeof b);
      //   同事声明多个变量并使用
      var c = 5,
        d = "hello";
      console.log(c, d);
      console.log(typeof c, typeof d);
    </script>
  </body>
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